Process control systems typically comprise one or more process controllers communicatively coupled to an operator workstation. The one or more process controller is furthermore communicatively coupled to at least one field device. The communication between the process controller and the field device(s) may be via an analog, a digital or a hybrid communication protocol. Normally, a number of input/output (I/O) modules, or I/O cards, are arranged in the communication path between a process controller and the field devices. The I/O modules form an interface which enables communication between process controllers and field devices.
The field devices, such as device controllers, valve actuators, valve positioners, switches and transmitters, perform functions within the process controlled by the process control system. The field devices send signals to the process controller(s), for example in the form of process variable values, wherein the process controller(s) uses the signal information to implement a control routine, and generate control signals that are sent to the field devices to control the operation of the process.
Configuration, or set-up, of a connection between the process control system and the field devices has traditionally required manual labour, typically carried out by two people. One person being located in the electrical room where the I/O modules are located, and another person in the process environment at the location of the field devices. Connections of cables from I/O modules to field devices have by these people been noted on paper for later basis of marshalling in the process control system. Marshalling refers to the process of defining which I/O module is connected to which field device.
U.S. Pat. No. 8,374,094 discloses methods and systems to verify a communication path between a field device and a process controller in a process control system. In particular, this document discloses a mobile verification controller for verifying a communication path between a process controller and a field device. The verification controller verifies a communication path by sending a command signal to one portion of the process control system and receiving a reception signal from a second portion of the process control system. The verification controller may send a command signal to a verification junction box, coupled between a field device and an I/O card. The verification controller may also send an instruction to the process controller indicating which I/O card to monitor for a verification signal. In response to receiving the command signal, the verification junction box transmits a verification signal to a communicatively coupled I/O card. The I/O card forwards the verification signal to a coupled process controller. The process controller then sends a reception signal to the verification controller. The verification signal may include an identifier of the I/O card that received the verification signal. Upon receiving the reception signal, the verification controller compares the identifier of the I/O card that received the verification signal to the specified I/O card. If the I/O card identifiers match, the communication path is classified as verified.
The procedure disclosed in U.S. Pat. No. 8,374,094 is a validation procedure, which requires that the cable configuration, i.e. connections between I/O cards and field devices, has already been performed.